Added custom path ability

[ashleybrgr]

Allows the option to specify a custom bundle path as per git issue #131. Supports dependencies using Swift Package Manager since the package manager does not have the ability to copy over dependency resources.

[efirestone]

I'm not a maintainer of the project, but the diff looks good to me (and we're interested in getting this change as well).

A possible couple improvements for consideration:

• Define JSONDataCallback as () throws -> Data rather than () -> Data?, with the thought being that a failure to get the data is really an error (there is no "successful" case where no data is returned). This is mostly just an API clarification.
• Rather than defining MetadataManager.init as:

public init (JSONDataCallback: JSONDataCallback? = nil)

instead define it as

public init (JSONDataCallback: JSONDataCallback = defaultDataCallback)

where defaultDataCallback does the standard behavior of looking up the data from the local bundle. This has two small advantages:

• The API is clearer. There is no guessing what nil means in the API.
• There is no internal dependency on the local bundle's file. defaultDataCallback would be a static function, so after initialization the class has zero notion of the default bundle and its resources.

[efirestone]

@marmelroy, any chance of landing this soon? We'd love to be able to adopt this project but require this addition.

[phoney]

I recommend that the metadataPath is a file URL not a String. A String can be anything. You can validate that the URL is a fileURL. The code doesn't change much but using a URL here would make the intention more clear and probably reduce some user bugs.

[marmelroy]

Thanks all and sorry for the delay with this. I think this is a great improvement and will add it to the next release.